Aluminum alloy



' Be it "known .that I, ANDRE Patented Dec. 9 1924.

UNITED STATES 1,518,321 PATENT OFFICE.

Arizona seven, or rARIs'FRANoE.

1T0 Drawing in Aluminum Alloys; and I do hereby declare the following tobe a full, clear, and exact description of the invention, such as willenable. others skilled in the art to which I it appertains to make anduse the same.

This invention relates to aluminum alloys and processes for themanufacture thereof, and has for its object the manufacture ofa li htalloy, the basis of which is aluminum, which possesses superiorqualities of resistance to rupture, of elasticity and of extensibility,together with practically negligible coefficients of dilation andcontraction, and a lowdensity. This alloy which consists essentially ofthe combination of the following constituents: aluminum, copper,manganese, magnesium, lead and carbon, is free from the striae orfilaments of oxide of aluminum that form lines of rupture and lendsitself very well to machining and to autogenous welding; it isunoxidable and susceptible of acquiring a beautiful polish. According tothis invention the process of manufacturing this alloy consistsessentially in combining carbon with the metallic constituents-of thealloy in the bath, while preventing the oxidation of the metal byshielding the surface of the bath from the effects of the contact of theair. The combination of the carbon in raphitic form is advantageouslyobtaine by incorporating with the bath finely powdered carbon, derived,for example, from charcoal and assisted by stirring; the surface of thebath being shielded from the action of air during this carbon treatmentby means of at protecting layer, for example of charcoal floating on thesurface of the bath, or by any other suitable or knownmethod.

In practice, theoperati'on is performed as follows The cupro-manganesemixture is first prepared with the required proportion, the greatestportion of the' aluminum intended to constitute the alloy is thenmelted, and powdered and broken'charcoal is introduced in the aluminumbath from the beginning of the melting. The previously pre aredcupro-manganese mixture is then ad ed to the bath, and the temperatureis raised. The

- ALUMINUM 'ALLoY.

Application filed September 11, 1922. Serial No. 587,582.

remainder of the aluminum is subse uently added and the temperature isthen a lowed to fall somewhat. Finally the magnesium and the lead areadded and the metallic alloy so obtained is cast into moulds.

The operation isadvantageously effectuated in a covered crucible orthelike, which is only uncovered during the time necessary for thesuccessive additions of the materials and for the mixing. The lattermust be frequent, and care must be taken to add to the bath newquantities of powdered charcoal at each. open ng of the crucible or thelike,

so as to ensure the proper combination of the carbon with the alloy. Asit has been stated above, all oxidation of the metal of the bath will beprevented by the layer of broken-up charcoal floating on its surface.Finally, the metal is suitably reheated before use. 7

The following typical. composition of a rupture resisting alloy is givenas a particular example of an alloy according to this invention Aluminum93.92 Copper 4.25 Magnesium 0.79 ifanganese 0.80 'ead Carbon} The alloycomprises also traces o'f,silico11 and, it may be, of iron, which may becon- 'tained as impurities in the metals used s constituents.-

Once reheated and rolled, for instance in the shape of plates of 20 mm.in thickness, the metal obtained gives approximately the followingcharacteristic coefficients Kg. Resistance to rupture 43.5 Coefficientof elasticity 25 Coefficient of extension 20.3 Coefficient ofconstriction 0.38 Density (about) 2.78

It will be understood that by suitable reheating and rolling, the abovementioned coefficients may be somewhat varied.

The particular process of manufacture, of this alloy willnow bedescribed, as an example The cupro-manganese mixture is prepared in theproportions of-425-of copper to'0.80 of manganese. .About three-quartersof the whole aluminum are melted, powdered and broken coalbeing-introduced into the mass, and the said previously preparedcupromanganese mixture is added. The temperature of the bath is raisedto about 950 C.

for nearly two hours. The remaining aluminum is then added and thetemperature is allowed to fall to about 800 C. The mixture is wellstirred and the heating continued at the same temperature. Finally thelead and themagnesium are added, tak- 'ing care that the magnesium doesnot rise to the surface of thebath. The metal is stirred and skimmed andthe alloy obtained is cast into ingots or pigs, withthe usualprecautions for casting aluminum. The metal is finally reheated duringabout 2 to 3 hours.

The alloy so manufactured lends itself to direct machining by rolling,drawing, etc.,

the metal having obtained its characteristic properties withoutquenching or other particular heat treatment:

I claim:

1. A process of manufacturing an aluminum alloy containing copper,manganese, magnesium and lead which com rises maintaining the mixturemolten whl e protected on its surface by a layer of finely dividedcarbon containing material and stirring the -metal while so protected tocause the carbon to enter the metal. v p

2. A strong, ductile alloy of light weight composed of about 93.92%aluminum, 4.25% copper 0.79% magnesium, 0.80% manganese and 0.24% leadand carbon.

In testimony that I claim the foregoing as my invention, I have si nedmname.

. t ANTRE EYER.

